Rasool Muhammad Hammad, Ahmad Maqsood
Department of Petroleum Geosciences, Universiti Teknologi Petronas, Seri Iskander 31750, Malaysia.
Molecules. 2023 Jul 31;28(15):5784. doi: 10.3390/molecules28155784.
Shale rock swelling poses a significant challenge during drilling a well, leading to issues related to wellbore instability. Water-based mud with specific shale inhibitors is preferred over oil-based drilling mud due to its lower environmental impact. Recently, ionic liquids (ILs) have emerged as potential shale inhibitors due to their adjustable properties and strong electrostatic attraction. However, research has shown that the most commonly used class of ILs (imidazolium) in drilling mud are toxic, non-biodegradable, and expensive. Deep Eutectic Solvents (DESs), the fourth generation of ionic liquids, have been proposed as a cheaper and non-toxic alternative to ILs. However, ammonium salt-based DESs are not truly environmentally friendly. This research explores the utilization of Natural Deep Eutectic Solvent (NADES) based on Epsom salt (a naturally occurring salt) and glycerine as a drilling fluid additive. The drilling mud is prepared according to API 13B-1 standards. Various concentrations of NADES-based mud are tested for yield point, plastic viscosity, and filtration properties for both aged and non-aged samples. The linear swell meter is used to determine the percentage swelling of the NADES-based mud, and the results are compared with the swelling caused by KCl- and EMIM-Cl-based mud. FTIR analysis is conducted to understand the interaction between NADES and clay, while surface tension, d-spacing (XRD), and zeta potential are measured to comprehend the mechanism of swelling inhibition by NADES. The findings reveal that NADES improves the yield point and plastic viscosity of the mud, resulting in a 26% reduction in mudcake thickness and a 30.1% decrease in filtrate volume at a concentration of 1%. NADES achieves a significant 49.14% inhibition of swelling at the optimal concentration of 1%, attributed to its ability to modify surface activity, zeta potential of clay surfaces, and d-spacing of clay layers. Consequently, NADES emerges as a non-toxic, cost-effective, and efficient shale inhibitor that can replace ILs and DESs.
在钻井过程中，页岩膨胀带来了重大挑战，导致井筒不稳定等问题。由于对环境影响较小，含有特定页岩抑制剂的水基泥浆比油基钻井泥浆更受青睐。近年来，离子液体（ILs）因其可调节的性质和强大的静电吸引力而成为潜在的页岩抑制剂。然而，研究表明，钻井泥浆中最常用的一类离子液体（咪唑鎓）有毒、不可生物降解且价格昂贵。作为第四代离子液体的深共晶溶剂（DESs）已被提议作为离子液体的一种更便宜且无毒的替代品。然而，基于铵盐的深共晶溶剂并非真正环保。本研究探索了基于泻盐（一种天然存在的盐）和甘油的天然深共晶溶剂（NADES）作为钻井液添加剂的应用。钻井泥浆按照API 13B - 1标准制备。对不同浓度的基于NADES的泥浆进行测试，以测定老化和未老化样品的屈服点、塑性粘度和过滤性能。使用线性膨胀仪测定基于NADES的泥浆的膨胀百分比，并将结果与基于KCl和EMIM - Cl的泥浆引起的膨胀进行比较。进行傅里叶变换红外光谱（FTIR）分析以了解NADES与粘土之间的相互作用，同时测量表面张力、d间距（X射线衍射）和zeta电位以理解NADES抑制膨胀的机制。研究结果表明，NADES提高了泥浆的屈服点和塑性粘度，在浓度为1%时，泥饼厚度降低了26%，滤液体积减少了30.1%。在最佳浓度1%时，NADES对膨胀的抑制率高达49.14%，这归因于其能够改变表面活性、粘土表面的zeta电位以及粘土层的d间距。因此，NADES成为一种无毒、经济高效的页岩抑制剂，可替代离子液体和深共晶溶剂。
